1. Field of the Invention
The present invention relates to a projector device adapted to guide light from a light source to an optical system to generate image light for magnification projection on a forward screen.
2. Description of Related Art
A conventional projector device of this type includes a casing having disposed therein a light source and an optical system including a polarization beam splitter, a polarizing plate, liquid crystal panels, a projection lens, etc. A discharge emission lamp unit such as a halogen lamp and a metal halide lamp is used as the light source.
The lamp unit includes a lamp and a reflector for reflecting light emitted from the lamp toward the optical system. The lamp is formed by enclosing a luminous body inside a quartz bulb. The lamp is cooled by a lamp cooling fan because the lamp has a shortened life when the lamp has a temperature exceeding a limit temperature.
It is known that in light emission of the lamp, the temperature at the vertically upper side of the quartz bulb is higher than the temperature at the lower side thereof, which results in the temperature difference between above and below the quartz bulb. This temperature difference between above and below is the greatest at the position where the luminous body is enclosed in the quartz bulb. In order to fully bring out the performance of the lamp, it is necessary to maintain the temperature of the lamp below the limit temperature, as well as to cool the lamp such that the temperature difference between above and below is held within a certain range.
Accordingly, there has been known a projector device having an air introduction opening for introducing air drawn from the lamp cooling fan into the lamp unit, which is provided at the vertically upper side of the lamp unit such that the air hits the vertically upper side of the quartz bulb (see JP 7-281296, A).
However, if the above projector device is set by being hung from a ceiling, then the setting of the device will be vertically reversed. Consequently, the air introduced from the air introduction opening will hit the vertically lower side of the quartz bulb.
In this case, the vertically lower side of the quartz bulb is excessively cooled, which results in an increased temperature difference between the vertically upper and lower sides of the quartz bulb. Therefore, there has been a problem in that the above projector device cannot be set by being hung from a ceiling.